<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>42js</title>
    <style>
        body,div{margin:0;padding:0;}
        div{
            width:100px;
            font-size:25px;
            color:#00ff00;
            text-align:center;
            line-height:40px;
            margin:50px auto;
            background-color:#3333ff;
            border-radius:50%;
            cursor:pointer;
        }
    </style>
</head>
<body>
    <div>调试</div>
</body>
</html>